ML20211E351

Responds to 860502 Request for Review of Unresolved Items in Insp Rept 50-312/86-08 Re 124-volt Dc Batteries.Encl Safety Evaluation Concludes Seismic Vibrations Could Lead to Battery Failure & Loss of 125-volt Dc Sys

ML20211E351
Person / Time
Site:	Rancho Seco
Issue date:	10/15/1986
From:	Miraglia F Office of Nuclear Reactor Regulation
To:	Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
TAC-61456, NUDOCS 8610220424
Download: ML20211E351 (3)

See also: IR 05000312/1986008

Text

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, October 15, 1986

MEMORANDUM FOR: Dennis F. Kirsch, Director

Division of Reactor Safety and Projects

Region V

FROM: Frank J. Miraglia, Director

Division of PWR Licensing-B

Office of Nuclear Peactor Regulation

SUBJECT: TRANSFER OF LEAD RESPONSIBILITY FOR REVIEW 0F TECHNICAL ISSUES

ASSOCIATED WITH DEGRADED BATTERIES (TIA 86-4 FM)

REFERENCE: Memorandum from D.F. Kirsch to F.J. Miraglia,

Transfer of Lead Responsibility on Degraded

Batteries at Rancho Seco, dated May 2, 1986.

In the referenced memo, you requested that we assume responsibility for the

review of certain technical issues identified in NRC Inspection Report

50-312/86-08 that involve several unresolved items concerning the licensee's

124 volt DC station batteries. This request was clarified during a telephone

conversation between NRR and Region V on June 5, 1986 with an agreement that

NRR should address the following concerns:

(1) Define the safety significance of the NRC inspectors findings as they

relate to battery seismic qualification and operability.

(2) Provide NRR's technical justification for the necessity of performing the

IEEE 450 " performance" and " service" testing.

We have completed our evaluation _and have concluded, due to the reported

deterioration of the cell plates and improper cell spacing, seismic vibrations

could have led to battery failure and loss of the 125 volt DC system.

Concerning surveillance program adequacy, we conclude that the IEEE 450

specified " performance" and " servi.ce" tests are necessary in order to

demonstrate compliance with the requirements of General Design Criterion 17

of Appendix A to 10 CFR 50. Our Safety Evaluation is attached for your

information. This completes TIA 86-4 FM.

Sincerely,

Original alanua .ay

Prook J. Miraglia

8610220424 861015 2

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ADOCK 0500 Frank J. Miraglia, Director

Division of PWR Licensing-B

Office of Nuclear Reactor Regulation

Enclosure: As stated

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MEMORANDUM FOR: Dennis F. Kirsch, Director

Division of Reactor Safety and Projects

Region V

FROM: John F. Stolz, Director

PWR Project Directorate #6

Division of PWR Licensing-B

SUBJECT: TRANSFER OF LEAD RESPONSIBILITY FOR REVIEW 0F TECHNICAL ISSUES

ASSOCIATED WITH DEGRADED BATTERIES (TIA 86-4 FM)

REFERENCE: Memorandum from D.F. Kirsch to F.J. Miraglia,

Transfer of Lead Responsibility on Degraded

Batteries at Rancho Seco, dated May 2, 1986.

In the referenced memo, you requested that we assume responsibility for the

review of certain technical issues identified in NRC Inspection Report

50-312/86-08 that involve several unresolved items concerning the licensee's

124 volt DC station batteries. This request was clarified during a telephone

conversation between NRR and Region V on June 5, 1986 with an agreement that

NRR should address the following concerns:

(1) Define the safety significance of the MRC inspectors findings as they

relate to battery seismic qualification and operability.

~(2) Provide NPR's technical justification for the necessity of performing the

IEEE 450 " performance" and " service" testing.

We have completed our evaluation and have concluded, due to the reported

deterioration of the cell plates and improper cell spacing, seismic vibrations

could have led to battery failure and loss of the 125 volt DC system.

Concerning surveillance program adecuacy, we conclude that the IEEE 450

specified " performance" and " service" tests are necessary in order to

demonstrate compliance with the requirements of General Design Criterion 17

of Appendix A to 10 CFR 50. Our Safety Evaluation is attached for your

information. This completes TIA 86-4 FM.

Sincerely,

John F. Stolz, Director

PWR Project Directorate #6

Division of PWR Licensing-B

Enclosure: As stated

DISTRIBUTION SMiner

Docket File GKalman

NRC PDR RWeller

Local PDR RIngram

Memo File

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Enclosure

Rancho Seco Nuclear Generating Station

Safety Evaluation

Seismic Qualification / Operability

Concern:

Define the safety significance of the NRC inspectors findings as they

relate to battery seismic qualification and operability.

Evaluation

The concerns raised by the NRC Inspection Report 50-312/86-08 are the

potentially unsatisfactory seismic capability due to an as-found

condition different from that of the design, and battery seismic

capability degradation due to deterioration of the cell plates in the

area of their connection to the cell posts. Based on seismic testing,

the vendor (GNB) of the Rancho Seco batteries specified that the gap

spacing between the end cell and the end stringer of the battery rack ,

should not be greater than 1/4 inch and the gap spacing between the cell

and the side stringer of the battery rack should be less than 3/8 inch.

The NRC inspector's report indicates that gap spacings greater t.han those

specified were found at Rancho Seco. _

The significance of this deviation is that in the event of an earthquake

there could be excessive inter-cell and cell to rack movement. This

excessive differential movement could result in impacts causing damage to

the cell containers. Further, with gaps present, the major restraint on

cell movement may be the inter-cell connectors and the cell terminal

posts. The reported deterioration of the cell plates in the area of the

cell posts and the additional stress on the posts through the connectors

due to seismic vibrations could lead to battery failure and the loss of

the 125 volt DC system.

Surveillance Program

Concern:

Provide NRP's technical justification for the necessity of performing the

IEEE 450 " performance" and " service" testing.

Evaluation

The " Performance" test demonstrates the purchased capacity of the battery

whereas the " service test" demonstrates the ability of the battery tn

meet its design safety function, commonly known as duty cycle (the two

j

hour test in which the largest one minute load and steady loads are

supposed to be adequately supplied by the hattery). The performance test

assures " capacity" whereas the service test assures " capability" as

required by GDC 17 to be the safety function of onsite, Class IE DC

systems. The licensee has committed in Section 8.1 of their FSAR to

comply with NRC General Design Criteria.

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